1. Field of the Invention
The present invention relates to a method for manufacturing a stripe-patterned metal plate which has a stripe pattern brought about by the arrangement of different kinds of metal sheet blanks, each of which has a colour different from the other. Further the present invention is concerned with a clad plate having a stripe pattern, manufactured by placing on a matrix metal plate a stripe-patterned metal plate prepared in the aforesaid method and integrally bonding both metal plates.
2. Description of the Prior Art
Hithereto, for manufacturing personal ornaments, adornments and other industrial art objects such as watch bands, bracelets, cigarette lighters, brooches, rings, buckles, cigarette cases, pendants, neck tie pins, cuffs buttons or the like, usually a clad plate is used and the clad plate is constructed of different kinds of metal plates, each of which has a colour different from the other.
Before describing the present invention, the conventional clad plates will be briefly described below with reference to FIG. 1 to 5.
Typical clad plates are as illustrated in FIG. 1 to 3 and are manufactured by placing cladding plate B on a matrix plate A of metal material different from that of said cladding plate B and then integrally bonding both metal plates by way of pressing, soldering or the like.
The clad plate as designated by the reference numeral 1 in FIG. 1 is referred to as a full clad plate, while the clad plate as designated by the reference numeral 2 in FIG. 2 is a so-called inlay type clad plate which is constructed of a matrix plate A and a cladding plate B placed thereon, said cladding plate B extending in the longitudinal direction and having the exposed areas of the matrix plate A on the both sides thereof.
Such simple structured clad plates as illustrated in FIG. 1 and 2 can be manufactured with less difficulty by placing the cladding plate B on the matrix plate A in an appropriate manner and then rolling the layer assembly of the both plates.
In the case of clad plate 3 in FIG. 3, however, where several strips of cladding plate B extend in the longitudinal direction so as to provide a different type of stripe pattern, multi-layer rolling is difficult to be carried out. The finer the stripe pattern is, the more difficult the rolling operation becomes. If three strips of cladding plate B of gold alloy are placed on a matrix plate A of stainless steel with a distance of 2 to 5 mm between each strip, multi-layer rolling is unsatisfactorily conducted as illustrated in FIG. 4, and causes the cladding plates B to be deformed into a snake-like motion pattern. Thus it is almost impossible with the conventional method to manufacture a clad plate with such a fine stripe pattern without any deformation or distortion.
To prevent such deformation or distortion in a stripe pattern it was proposed that a plurality of grooves 4 (see FIG. 5) be formed on the matrix plate A to receive the cladding plates B therein and the layer assembly of the matrix plate A and cladding plates B would be subjected to a rolling operation. It is recognized with this improved conventional method, however, that as the rolling operation is conducted, the cladding plates B tend to overflow the grooves, resulting in an irregular stripe pattern if fine cladding plates B having a width, for instance, of less than 2 mm, are extended with a narrow clearance therebetween. Therefore, plating is employed if finer stripe pattern is required. A drawback of the plating method, however, is that peeling-off takes place over the plated area during the course of plastic deformation, such as bending operations or the like.
U.S. Pat. No. 3,165,824 discloses a method of producing a stripe-patterned composite material. This method is not entirely practical and satisfactory in that the metal intermediate plate is rolled in such a manner that the resultant composite material frequently has the stripes which are not fully straight, i.e., somewhat serpentine. In addition, the metal intermediate plate of a rectangular cross-section sometimes falls to be rolled into a rectangular cross-section, that is to say, it is rolled into a rhombic cross-section.
U.S. Pat. No. 3,165,825 discloses a method of producing a helical patterned composite material. The metal intermediate plate of a rectangular cross-section is rolled by a pair of grooved rolls into a cross-sectionally circular rod. The use of the grooved rolls requires a relatively long metal intermediate plate. When a relatively short metal plate intermediate is to be rolled by such grooved rolls, at least one end portion of the metal plate intermediate has to be held by a suitable gripping means. As a result, the non-processed end portion of the metal plate intermediate, serving as the gripping portion, is not used as a final product. This is quite undesirable from an economic point of view particularly when precious metals such as 18 K gold alloys are used to produce the composite material. Another disadvantage is that when the metal plate intermediate of a short length is hot rolled using such grooved rolls, it becomes cooled rapidly. As a result, the hot rolling is not carried out efficiently.
In view of this background, an improved method for manufacturing a stripe-patterned metal plate having a stripe pattern provided by cladding and not by plating has been looked for, with the stripe pattern being excellent in strength and wear resistance and strong enough to withstand heavy plastic deformation.